My mom doesn’t really want to rent. I tried talking her into it today, but she seems willing to wait to buy until she comes across a really good deal (I’ve warned her that it might be a few years). She is also not going to sell her home in PA. My dad is content with their current situation of flying to Seattle every few months (he hates change) and would probably spend less time there then my mom, who would be there at least half the year. As for living with my sister and her kids–I think she needs her own privacy, and this is not the best option for her.
We decided that our safest option is to wait and see what happens with the separation, and if he gets half of everything, so be it. We’ll worry about the house for mom later.
CA renter, you make a good point that it might be nice for my mom to be around the grandkids during transition time. I think she would be willing to live with them temporarily while everything settles (I had no idea how excruciatingly long the whole divorce process is!). Maybe by then the Seattle housing market will be more affordable.